The elucidation of substrate–protein interactions is an important component of the drug development process. Due to the complexity of native cellular environments, elucidating these fundamental biochemical interactions remains challenging. Photoaffinity labeling (PAL) is a versatile technique that can provide insight into ligand‐target interactions. By judicious modification of substrates with a photoreactive group, PAL creates a covalent crosslink between a substrate and its biological target following UV‐irradiation. Among the commonly employed photoreactive groups, diazirines have emerged as the gold standard. In this Minireview, recent developments in the field of diazirine‐based photoaffinity labeling will be discussed, with emphasis being placed on their applications in chemical proteomic studies.

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Polylactide (PLA) is a promising biosourced and biodegradable polymer substitute for traditional petroleum-based products. Despite its recognized potential, its widespread adoption is restricted by its brittleness and low ductility and, thus, to enhance its material properties, plasticizers must be blended with PLA to lower the glass transition temperature (T g) and impart flexibility into the blend. As such, this work focused on the synthesis of a family of biosourced plasticizers for applications in flexible food packaging using glycerol, succinic anhydride, and alcohols of varying chain lengths. The effect of the chemical structure on plasticization performance, migration, blend morphology, and toxicity was evaluated and compared to the commercial plasticizer acetyl tributyl citrate. Plasticizer/PLA blends were prepared using solvent-casting as well as melt-mixing to produce thin films and bulk specimens. At loadings of 20 wt %, improved flexibility (up to 435% elongation) was observed in films with the glycerol plasticizers relative to neat PLA (6% elongation), while T g’s were reduced by up to 45 °C from that of neat PLA (T g ∼ 60 °C). Phase morphologies evaluated with scanning electron microscopy showed good incorporation of the plasticizers into the PLA matrix. Leaching behavior of the plasticized blends was evaluated in different food simulants and showed that plasticizers composed of branched or longer alkyl chains produced two- to sixfold lower migration rates compared to those with short alkyl chains. Finally, plasticizer candidates were shown to be nontoxic and did not impact HepG2 cell viability over a period of 7 days in an in vitro mammalian cell assay.

Gas checks are visible fleck‐shaped defects that occur on the surface of poly(vinyl chloride) (PVC) films during industrial calendering. Films containing these surface defects often do not meet minimum product specifications and therefore must be disposed of or recycled, resulting in increased cost and material waste. Currently, gas checks are controlled by keeping film gauge low and through trial‐and‐error modifications of processing parameters by calender operators. In this work, our group developed a series of chemical additives that can be blended with PVC to prevent the formation of gas check defects. We found that a series of poly(caprolactone) (PCL)‐based compounds with diester linkers and alkyl chain cappers were all effective at preventing the formation of gas checks during calendering, with additive concentrations as low as 8 phr producing films with no gas checks. We found that the blends produced with our additives had higher melt viscosities than those produced with additives that do not remove gas checks, suggesting that viscosity plays an important role in preventing gas check defects.

A family of poly(caprolactone) (PCL)-based oligomeric additives was evaluated as plasticizers for poly(vinyl chloride) (PVC). We found that the entire family of additives, which consist of a PCL core, diester linker, and alkyl chain cap, were effective plasticizers that improve migration resistance. The elongation at break and tensile strength of the blends made with the PCL-based additives were comparable to blends prepared with diisononyl phthalate (DINP), a plasticizer typically used industrially, and diheptyl succinate (DHPS), an alternative biodegradable plasticizer. Increasing concentration was found to decrease glass transition temperature (T g ) and increase elongation at break, confirming their role as functional plasticizers. We found that all of the PCL-based plasticizers exhibited significantly reduced leaching into hexanes compared to DINP and DHPS. The PCL-based plasticizers with shorter carbon chain lengths reduced leaching more than those with longer carbon chain lengths.